Thermal instability in an electron-ion magnetized plasma which is relevant in the intragalactic medium (IGM) of galaxy clusters, solar corona, and other two-component plasma objects is investigated. We apply the multicomponent plasma approach when the dynamics of all species is considered separately through the electric field perturbations.General expressions for the dynamical variables obtained in this paper can be applied for a wide range of astrophysical and laboratory plasmas also containing neutrals and dust grains. We assume that background temperatures of electrons and ions are different and include the energy exchange in the thermal equations for the electrons and ions along with the collisional momentum exchange in the equations of motion. We take into account the dependence of collision frequency on the density and temperature perturbations. The cooling-heating functions are taken for both electrons and ions. A condensation mode of thermal instability has been studied in the fast sound speed limit. A new dispersion relation including the different electron and ion cooling-heating functions and other effects mentioned above has been derived and its simple solutions for growth rates in the limiting cases have been found. We have shown that the perturbations have an electromagnetic nature. The crucial role of the electric field perturbation along the background magnetic -2field in the fast sound speed limit has been demonstrated. We have found that at conditions under consideration, the condensation must occur along the magnetic field while the transverse scale sizes can be both larger and smaller than the longitudinal ones. The results obtained can be useful for interpretation of observations of dense cold regions in astrophysical objects.

New instabilities in multicomponent cold magnetized accretion disks are found using not the magnetohydrodynamics (MHD) framework but the equations of motion and continuity for each disk component and Maxwell’s equations, where the magnetic field perturbations are substituted by the electric field perturbations. The stationary velocities of magnetized charged particles are taken to be not the Keplerian velocity, as it is adopted in the astrophysical literature using the MHD approach for studying disks, but as the electric and gravitational drifts in the external magnetic field (at the neglect of collisions). The compressibility is taken into account. There are considered axisymmetric as well as nonaxisymmetric perturbations in the form of columns and spokes. The growth rates of instabilities being found can be considerably larger than the growth rate of the well-known magnetorotational instability studied in the MHD framework.

Electromagnetic streaming instabilities of multicomponent collisional magnetized accretion disks are studied. Sufficiently ionized regions of the disk are explored where there is strong collisional coupling of neutral atoms with both ions and dust grains simultaneously. The steady state is investigated in detail and the azimuthal and radial background velocities of species are calculated. The azimuthal velocity of ions, dust grains, and neutrals is found to be less than the Keplerian velocity. The radial velocity of neutrals and dust grains is shown to be directed inward of the disk. The general solution for the perturbed velocities of species taking into account collisions and thermal pressure is obtained. The effect on the collisional frequencies, due to density perturbations of charged species and neutrals, is included. It is shown that dust grains can be involved in the fast electromagnetic perturbations induced by the ions and electrons through the strong collisions of these grains with neutrals that in turn have a strong collisional coupling with the ions. The dispersion relation for the vertical perturbations is derived and its unstable solutions due to different background velocities of ions and electrons are found. The growth rates of the streaming instabilities considered can be much larger than the Keplerian frequency.

Using the multi-fluid approach, we investigate streaming and thermal instabilities of the electron-ion plasma with homogeneous cold cosmic rays drifting perpendicular to the background magnetic field. Perturbations across the magnetic field are considered. The back-reaction of cosmic rays resulting in the streaming instability is taken into account.The thermal instability is shown not to be subject to the action of cosmic rays in the model under consideration. The dispersion relation for the thermal instability has been derived which includes sound velocities of plasma and cosmic rays, Alfvén and cosmic ray drift velocities. The relation between these parameters determines the kind of thermal instability from Parker's to Field's type instability. The results obtained can be useful for a more detailed the investigation of electron-ion astrophysical objects such as galaxy clusters including the dynamics of streaming cosmic rays.

We investigate electromagnetic buoyancy instabilities of the electron-ion plasma with the heat flux based on not the magnetohydrodynamic (MHD) equations, but using the multicomponent plasma approach when the momentum equations are solved for each species. We consider a geometry in which the background magnetic field, gravity, and stratification are directed along one axis. The nonzero background electron thermal flux is taken into account. Collisions between electrons and ions are included in the momentum equations. No simplifications usual for the onefluid MHD-approach in studying these instabilities are used. We derive a simple dispersion relation, which shows that the thermal flux perturbation generally stabilizes an instability for the geometry under consideration. This result contradicts to conclusion obtained in the MHD-approach. We show that the reason of this contradiction is the simplified assumptions used in the MHD analysis of buoyancy instabilities and the role of the longitudinal electric field perturbation which is not captured by the ideal MHD equations. Our dispersion relation also shows that the medium with the electron thermal flux can be unstable, if the temperature gradients of ions and electrons have the opposite signs. The results obtained can be applied to the weakly collisional magnetized plasma objects in laboratory and astrophysics.